[gridengine users] slot reservation

[Reuti]

Hi,

Am 01.07.2012 um 19:55 schrieb Steve Schmerler:

> This is probably an easy one, but I just can't figure it out by myself.
> 
> I recently activated reservation by setting max_reservation with "qconf
> -msconf". However, no slots seem to be reserved. Big parallel jobs
> submitted with "qsub -R y" still get back-filled by small ones of lower
> priority. Also, there are no entries about reservation in
> $SGE_ROOT/$SGE_CELL/common/schedule and the "RES" column in "qstat -g
> c"'s output is always zero.

This output is for Advance Reservation (`man qstat` section "OUTPUT FORMAT"). Not the one for reserving resources.


> I'm not sure if this is important, but all jobs have the same s_rt =
> h_rt = INFINITY and the scheduler's default_duration = INFINITY, too.
> Therefore we shouldn't see any runtime-related issues like low priority
> jobs backfill the big ones because of shorter default runtime.

Well, as SGE judges INIFINITY being smaller than INFINITY, always smaller jobs can slip in. As they are known to finish before additional resources are getting free (which are blocked by other jobs to infinity), they are backfilling the cluster all the time.

You will have to provide suitable runtimes for reservations to succeed for all jobs. As a start you can define the "default_duration" being one year or so, i.e. longer than your longest job. But it would be better to have correct estimations.


> Do I need to set anything else besides max_reservation to get slots
> reserved for pending jobs when other jobs finish (this is SGE 6.2u3)? 
> 
> Also, I may not fully understand what max_reservation is. Right now I
> set it to 128 which I assume is the max number of slots to be reserved

It depends on the size of the cluster. But usally around 32 should do.

-- Reuti


> per job. But according to [1], it is "The maximum number of resource
> reservations considered within a schedule interval." That sounds like I
> can also reserve other resources like memory. If so, do I need to
> specify what I want to reserve? 
> 
> Thanks.
> 
> best,
> Steve
> 
> [1] http://docs.oracle.com/cd/E24901_01/doc.62/e21978/management.htm
>    "3.1.2.9 How to Modify the Scheduler Configuration From the Command
>    Line"
> 
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